Analysis of microcystins and nodularin in drinking water using an Agilent Ultivo triple quadrupole LC/MS

Importance of the Topic

Microcystins and nodularin are potent hepatotoxins produced by cyanobacteria that can contaminate drinking water during algal blooms. Regulatory agencies such as the US EPA and WHO set stringent sub-ppb limits, making reliable detection essential to safeguard human and animal health.

Objectives and Study Overview

This application note illustrates the implementation of US EPA Method 544 for the simultaneous determination of six microcystin variants and nodularin in drinking water. The study focuses on demonstrating sensitivity, robustness, and compliance with regulatory guidelines through solid phase extraction and LC–MS/MS analysis.

Applied Methodology and Instrumentation

A 500 mL water sample undergoes filtration, SPE clean-up, concentration to dryness, and reconstitution in a 1:1 ultrapure water/methanol solution. Analysis employs dynamic multiple reaction monitoring (dMRM) for target transitions.
Instrumentation:

• Agilent 1290 Infinity II UHPLC with high-speed pump, cooled multisampler, and multi-column thermostat.
• Agilent Ultivo triple quadrupole LC/MS featuring Cyclone Ion Guide, Vortex Collision Cell, and Hyperbolic Quadrupoles.
• Agilent Jet Stream electrospray ionization source controlled via MassHunter software for data acquisition and reporting.

Main Results and Discussion

Extraction recoveries ranged from 82 % to 115 % for both low- and mid-level spikes, meeting EPA acceptance criteria. Calibration curves exhibited excellent linearity (R² > 0.99) across all analytes. Method precision over 17 hours showed peak area RSD < 10 % and retention time RSD < 1.7 %. Sensitivity allowed detection well below WHO and state advisory thresholds.

Benefits and Practical Applications

The compact UHPLC–MS/MS system delivers high-throughput, precise analysis of cyanotoxins, streamlining routine monitoring and quality assurance in environmental and water utilities laboratories. Its intuitive software accelerates method setup, data processing, and reporting.

Future Trends and Potential Applications

Advancements may include automated sample preparation, real-time on-site screening, and expanded analyte coverage. Miniaturized MS systems and cloud-based data analysis platforms could further enhance early warning capabilities for water quality management.

Conclusion

The combined Agilent 1290 Infinity II LC and Ultivo triple quadrupole MS offer a sensitive, reliable, and efficient workflow for trace-level quantification of microcystins and nodularin in drinking water, fully supporting EPA Method 544 requirements.

References

1. United States Environmental Protection Agency. Cyanobacteria/Cyanotoxins. Nutrient Policy and Data. Retrieved February 8, 2018.
2. United States Environmental Protection Agency. Causes and Prevention. Nutrient Policy and Data. Retrieved February 8, 2018.
3. United States Environmental Protection Agency. Drinking Water Health Advisory for the Cyanobacterial Microcystin Toxins; Office of Water, EPA 820/R-15/100, June 2015.
4. World Health Organization. Chemical Hazards in Drinking-Water: Microcystin-LR. Water Sanitation and Health. Retrieved February 8, 2018.
5. Shoemaker JA; Tettenhorst DR; de la Cruz A. Method 544: Determination of Microcystins and Nodularin in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS); EPA/600/R-14/474; US EPA Office of Research and Development, National Exposure Research Laboratory, February 2015.